A Denial of Service (DoS) vulnerability was found in the BigDecimal standard Ruby library. An attacker could cause a segmentation fault and crash the Ruby interpreter. This is due to the BigDecimal method mishandling certain large values. Almost every Rails application is vulnerable to this because ActiveRecord relies on this method.
You are advised to update your Ruby installation. There is a temporary fix on Github. This fix breaks valid formats supported by BigDecimal, so you are advised to plan migrating to a new Ruby version.